Analyzing the Potential of Drill Bits 3D Printed Using the Direct Metal Laser Melting (DMLM) Technology to Drill Holes in Polyamide 6 (PA6)

Drilling with standard twist drill bits is the most common method to create cylindrical holes. With the constant development of additive manufacturing technologies and easier access to additive manufacturing equipment, it is now possible to design and fabricate solid tools suitable for various machining applications. Specially designed 3D printed drill bits seem more convenient for standard and nonstandard drilling operations than conventionally made tools. The study described in this article aimed to analyze the performance of a solid twist drill bit made from steel 1.2709 using direct metal laser melting (DMLM), which was compared with that of a drill bit manufactured conventionally. The experiments involved assessing the dimensional and geometric accuracy of the holes made by the two types of drill bits and comparing the forces and torques occurring during the drilling of holes in cast polyamide 6 (PA6).


Introduction
Additive manufacturing (AM), also known as rapid prototyping (RP) or 3D printing, is a group of modern manufacturing processes able to create geometrically complex objects from 3D CAD data with little or no need for finishing operations. AM is increasingly common in the automotive, [1,2], aviation [3], biomedicine, medicine [4], food processing, maintenance and repair, education, and entertainment sectors. Like any other manufacturing process, AM has some shortcomings. The limitations relate to the types of materials, production capacity, surface quality, and post-processing operations [5]. The major advantage of AM is the possibility to create a ready-to-use part with final dimensions in one step. This, however, makes the process quite expensive.
Over the years, many studies have focused on the design and manufacture of finished elements in just one process [6]. An important variety of RP is rapid tooling (RT), which allows us to fabricate tools quickly. As described in [7], tools created through direct metal laser sintering can be improved by filling pores with high temperature epoxy resin to ensure higher compressive strength. Additionally, electroless nickel plating can be used to increase the material hardness and resistance to wear and abrasion; this, however, has no effect on the dimensional and geometric accuracy of the tool.
Despite rapid technological development, drilling is still the most common and bestknown method to make cylindrical holes. Drilling with additively manufactured tools is, however, a new solution, which requires researchers to investigate it thoroughly.

Materials and Methods
The experiments were carried out for two drill bits: one made of maraging steel 1.2709 3D printed through DMLM and the other, conventionally made of high-speed steel.
The 3D model of the additively manufactured twist drill bit was designed using Siemens NX. A Concept Laser M2 cusing DMLM-based machine was used for the printing. The process was performed in an argon atmosphere with an oxygen content of less than 0.1% for a layer thickness of 20 µm. The manufacturing time for one printed drill was approximately 20 h, and the cost was EUR 415. Maraging steel 1.2709 was used for the tool because of its excellent properties, for e.g., its high wear resistance, yield strength, and ultimate tensile strength, over a relatively wide range of temperatures. The drilling process generates friction and, consequently, high temperatures in the cutting zone. The chemical composition of the steel used for the tool is shown in Table 1. As the 3D printed drill bit had a low dimensional and geometric accuracy and high surface roughness, the tool was ground using three different machines. The equipment used for this purpose is illustrated in Figure 1.
guidelines on the fabrication and use of 3D printed tools in different industrial applications.
The key objective of the study described in this article was to assess the potential use of a solid cutting tool (drill bit) 3D printed from 1.2709 steel using direct metal laser melting (DMLM), by comparing its performance with that of a commercially available tool manufactured in a conventional way. The study also aimed to compare the dimensional and geometric accuracy of the holes made with the two types of drill bits, as well as the forces and torques observed during drilling.

Materials and Methods
The experiments were carried out for two drill bits: one made of maraging steel 1.2709 3D printed through DMLM and the other, conventionally made of high-speed steel.
The 3D model of the additively manufactured twist drill bit was designed using Siemens NX. A Concept Laser M2 cusing DMLM-based machine was used for the printing. The process was performed in an argon atmosphere with an oxygen content of less than 0.1% for a layer thickness of 20 µm. The manufacturing time for one printed drill was approximately 20 h, and the cost was EUR 415. Maraging steel 1.2709 was used for the tool because of its excellent properties, for e.g., its high wear resistance, yield strength, and ultimate tensile strength, over a relatively wide range of temperatures. The drilling process generates friction and, consequently, high temperatures in the cutting zone. The chemical composition of the steel used for the tool is shown in Table 1. As the 3D printed drill bit had a low dimensional and geometric accuracy and high surface roughness, the tool was ground using three different machines. The equipment used for this purpose is illustrated in Figure 1.  First, the shank and the face were ground using a Ponar-Tarnów RUP 28.45 FOS center grinding machine (Figure 1a). Then, the margin, the flank, and the face were shaped with a SAACKE UW-IC grinding machine (Figure 1b). Finally, the face and the chisel edge were corrected using an MRCM MR-20G drill bit sharpener (Figure 1c). Figure 2 depicts the different stages in the fabrication of the twist drill bit. Figure 2a shows the 3D model used to print the steel 1.2709 drill bit by using DMLM technology (Figure 2b). Figure 2c shows the drill bit finished by grinding.
ter grinding machine (Figure 1a). Then, the margin, the flank, and the face were sh with a SAACKE UW-IC grinding machine (Figure 1b). Finally, the face and the chise were corrected using an MRCM MR-20G drill bit sharpener (Figure 1c). Figure 2 depicts the different stages in the fabrication of the twist drill bit. Figu shows the 3D model used to print the steel 1.2709 drill bit by using DMLM techn ( Figure 2b). Figure 2c shows the drill bit finished by grinding. The dimensional and geometric accuracy of the 3D printed drill bit was assesse fore and after the grinding processes. The equipment used for this purpose was a d caliper (to measure the length of the printed tool before and after the finishing operat Mahr Federal MarCal 16 EWV digital diameter measuring tool (to determine the d diameter), a ZEISS O-INSPECT multisensory optical measuring machine (to measu point angle), and a Taylor Hobson Talyrond 365 roundness measuring instrume measure the shank cylindricity error). The influence of the process parameters on t mensional and geometric accuracy of the finished 3D printed drill bit (Figure 3a) w termined by analyzing the geometry and surface quality of the drill bit.
The other tool used for hole drilling was an HK 11020480 HSS drill bit by Atorn ure 3b). The tool has a point angle of 118°, a flute length of 94 mm, an overall length mm, and a cutting diameter of 11.5 mm.  The hole drilling tests were performed using 24 cylindrical specimens, 40 mm ameter and 30 mm in height, made of a crystalline/semi-crystalline polymer called amide (PA), which is produced by polycondensation of hexamethylene diamin adipic acid. The material has a density of approx. 1.14 g/cm³ and a melting point of 255 °C. Polyamides are characterized by good mechanical properties, i.e., high t strength, good resistance to abrasion, and a low coefficient of friction. Another imp benefit of PAs is their large dimensional stability at elevated temperatures. Because o The dimensional and geometric accuracy of the 3D printed drill bit was assessed before and after the grinding processes. The equipment used for this purpose was a digital caliper (to measure the length of the printed tool before and after the finishing operations), Mahr Federal MarCal 16 EWV digital diameter measuring tool (to determine the drill bit diameter), a ZEISS O-INSPECT multisensory optical measuring machine (to measure the point angle), and a Taylor Hobson Talyrond 365 roundness measuring instrument (to measure the shank cylindricity error). The influence of the process parameters on the dimensional and geometric accuracy of the finished 3D printed drill bit (Figure 3a) was determined by analyzing the geometry and surface quality of the drill bit. Figure 2 depicts the different stages in the fabrication of the twist drill bit. Figure 2a shows the 3D model used to print the steel 1.2709 drill bit by using DMLM technology ( Figure 2b). Figure 2c shows the drill bit finished by grinding. The dimensional and geometric accuracy of the 3D printed drill bit was assessed before and after the grinding processes. The equipment used for this purpose was a digital caliper (to measure the length of the printed tool before and after the finishing operations), Mahr Federal MarCal 16 EWV digital diameter measuring tool (to determine the drill bit diameter), a ZEISS O-INSPECT multisensory optical measuring machine (to measure the point angle), and a Taylor Hobson Talyrond 365 roundness measuring instrument (to measure the shank cylindricity error). The influence of the process parameters on the dimensional and geometric accuracy of the finished 3D printed drill bit ( Figure 3a) was determined by analyzing the geometry and surface quality of the drill bit.
The other tool used for hole drilling was an HK 11020480 HSS drill bit by Atorn (Figure 3b). The tool has a point angle of 118°, a flute length of 94 mm, an overall length of 142 mm, and a cutting diameter of 11.5 mm.  The hole drilling tests were performed using 24 cylindrical specimens, 40 mm in diameter and 30 mm in height, made of a crystalline/semi-crystalline polymer called polyamide (PA), which is produced by polycondensation of hexamethylene diamine and adipic acid. The material has a density of approx. 1.14 g/cm³ and a melting point of about 255 °C. Polyamides are characterized by good mechanical properties, i.e., high tensile strength, good resistance to abrasion, and a low coefficient of friction. Another important benefit of PAs is their large dimensional stability at elevated temperatures. Because of their The other tool used for hole drilling was an HK 11020480 HSS drill bit by Atorn ( Figure 3b). The tool has a point angle of 118 • , a flute length of 94 mm, an overall length of 142 mm, and a cutting diameter of 11.5 mm.
The hole drilling tests were performed using 24 cylindrical specimens, 40 mm in diameter and 30 mm in height, made of a crystalline/semi-crystalline polymer called polyamide (PA), which is produced by polycondensation of hexamethylene diamine and adipic acid. The material has a density of approx. 1.14 g/cm 3 and a melting point of about 255 • C. Polyamides are characterized by good mechanical properties, i.e., high tensile strength, good resistance to abrasion, and a low coefficient of friction. Another important benefit of PAs is their large dimensional stability at elevated temperatures. Because of their properties, PAs are used in a variety of industrial applications. They are commonly used in automotive and machine components, such as toothed wheels, bearings, bolts and nuts, pump components, couplings, cams, distributors, and drive shafts.
The material, characterized by good mechanical stability, stiffness, damping capacity, and resistance to abrasion, is frequently used for machine elements because it is easy to machine. Each polyamide specimen was placed in an Axon K72-125 four-jaw chuck, mounted on the table of an FOP AVIA VMC 800 vertical milling center ( Figure 4). The tests involved measuring the forces and torques by means of an HBM MCS10 multi-axial load cell. The force transducer was capable of simultaneously measuring the forces and torques along three axes (x, y, z). ring during drilling. The MCS10 transducer was connected to each of the eight channels available on an HBM MX840B universal measuring amplifier equipped with a 24-bit analog-to-digital converter. The measuring system also included a HBM WA/50MM-T inductive displacement transducer, to measure the axial displacement of the tool during drilling to correlate the tool position with the instantaneous values of the forces and torques during drilling. The measurement process was coordinated by Catman data acquisition software. The drilling tests using a VMC 800 vertical milling center did not involve applying any cutting fluid, which means that holes were drilled under dry lubrication conditions. Due to the prototypical nature of the printed drill bit, with no specific operating settings, the cutting speed and the feed rate were selected by following the recommendations of the producer of the HSS drill bit. The drilling was performed at two cutting speeds (20 and 30 m/min) and two feed rates (0.1 and 0.2 mm/rev). Each hole drilling test was run three times (Table 2). The load cell provides real three-dimensional images of the forces and torques occurring during drilling. The MCS10 transducer was connected to each of the eight channels available on an HBM MX840B universal measuring amplifier equipped with a 24-bit analogto-digital converter. The measuring system also included a HBM WA/50MM-T inductive displacement transducer, to measure the axial displacement of the tool during drilling to correlate the tool position with the instantaneous values of the forces and torques during drilling. The measurement process was coordinated by Catman data acquisition software.
The drilling tests using a VMC 800 vertical milling center did not involve applying any cutting fluid, which means that holes were drilled under dry lubrication conditions. Due to the prototypical nature of the printed drill bit, with no specific operating settings, the cutting speed and the feed rate were selected by following the recommendations of the producer of the HSS drill bit. The drilling was performed at two cutting speeds (20 and 30 m/min) and two feed rates (0.1 and 0.2 mm/rev). Each hole drilling test was run three times ( Table 2). All the signals providing information on the forces, torques, and tool displacements were filtered and analyzed using MATLAB.
As the signals representing the forces and torques during drilling were distorted signals, they were analyzed in the time and frequency domains. A fast Fourier transform (FFT) was used to convert the time-domain signals into frequency-domain signals. The Fourier transform X(jω) required to obtain the amplitude spectrum of the signal x(t) is given by the integral equation: where j 2 = −1 is the imaginary unit and e jω = cos ω + j sin ω. For digitally processed signals, a numerical method known as a discrete Fourier transform (DFT) is used. An efficient algorithm for the fast Fourier transform (FFT) is used to calculate the DFT. The DFT can be expressed as: where N is the number of specimens. The discrete value X(k) represents a complex number that provides information about the signal amplitude and phase. Under industrial conditions, the amplitude spectrum is usually determined as: The values of A(k) and x(n) have the same physical dimension. This article analyzes the amplitude spectra to determine the forces and torques occurring during drilling. For each measured signal, an FFT algorithm with a sampling frequency of 19.2 kHz was used to obtain a useful range of frequency from 0 to 9.6 kHz (according to the Nyquist-Shannon sampling theorem, also known as the Kotielnikow-Shannon theorem). For the analyzed force and torque signals, the proper frequency peaks were found for the drill bit revolution frequency. Figure 5 shows the forces, respectively, in the x, y and z directions and the amplitude spectra of the forces in the x and y directions, calculated on the basis of the FFT analysis for the drilling performed at a cutting speed of 548 (554) rev/min. The dimensional and geometric accuracy of the holes was assessed using a ZEISS Prismo Navigator coordinate measuring machine (Figure 6a). Figure 6b shows the measurement strategy to assess the hole accuracy. The straightness error was determined by measuring the generating lines in four angular positions, spaced every 90° using a Gauss-  The dimensional and geometric accuracy of the holes was assessed using a ZEISS Prismo Navigator coordinate measuring machine (Figure 6a). Figure 6b shows the measurement strategy to assess the hole accuracy. The straightness error was determined by measuring the generating lines in four angular positions, spaced every 90 • using a Gaussian filter with λc = 2.5 mm. The roundness error was calculated on the basis of 1500 points measured in five cross-sections, i.e., at depths of 5 mm, 10 mm, 15 mm, 20 mm, and 25 mm, using a Gaussian 2-15 UPR filter. The dimensional and geometric accuracy of the holes was assessed using a ZEI Prismo Navigator coordinate measuring machine (Figure 6a). Figure 6b shows the mea urement strategy to assess the hole accuracy. The straightness error was determined measuring the generating lines in four angular positions, spaced every 90° using a Gau ian filter with λc = 2.5 mm. The roundness error was calculated on the basis of 1500 poin measured in five cross-sections, i.e., at depths of 5 mm, 10 mm, 15 mm, 20 mm, and mm, using a Gaussian 2-15 UPR filter. The measurements were performed using a ZEISS VAST scanning probe with a ru ball 3 mm in diameter, at a scanning speed of 5 mm/s.

Results and Discussion
The influence of the manufacturing process on the dimensional and geometric acc racy of the finished 3D printed drill bit was determined by measuring its key paramete The tool after grinding had a point angle of 118°, a flute length of 71 mm, an overall leng of 134.5 mm, and a cutting diameter of 11.5 mm. The drill bit weighed 77.9 g. The measurements were performed using a ZEISS VAST scanning probe with a ruby ball 3 mm in diameter, at a scanning speed of 5 mm/s.

Results and Discussion
The influence of the manufacturing process on the dimensional and geometric accuracy of the finished 3D printed drill bit was determined by measuring its key parameters. The tool after grinding had a point angle of 118 • , a flute length of 71 mm, an overall length of 134.5 mm, and a cutting diameter of 11.5 mm. The drill bit weighed 77.9 g.
The conclusions concerning the differences between the 3D model and the finished drill bit were used to prepare guidelines on the fabrication and use of tools 3D printed from metal powders. Table 3 compares the basic parameters of the 3D model with those of the printed tool after grinding. From the measurement data in Table 3, it is evident that at the design stage the CAD model of the drill bit needs to include material allowances because of the inaccuracy of the printing process. The minimum radius allowance for a drill bit with a diameter of 12 mm should be 0.25 mm per side, with the total being 0.5 mm. This value seems sufficient to achieve high geometric and dimensional accuracy of the shank, the face, and the flank. Unfortunately, with this radius allowance it is not possible to grind the whole surface of the flute; some areas remain unfinished, as illustrated in Figure 2c. For this reason, it is recommended that at the design stage the radius allowance in the flute area should be increased to a minimum of 0.5 mm per side. While selecting the length allowances (along the tool axis), a designer should add 0.5−1 mm for facing and approximately 5 mm per center hole for center grinding. If the finishing process involves center grinding, it is not recommended to design a drill bit with a tip because it will have to be removed to make a center hole. In this study, the difference in the overall length between the printed tool and the commercially available tool was 15 mm. The length allowances were necessary for the following operations: first to create the center holes at both ends (2.5 mm × 2), so that the center grinding could be performed, and then to shape the drill bit tip (10 mm).
The dimensional and geometric accuracy of the shank of the 3D printed tool was measured before and after grinding. The measurements were taken in five cross-sections along the shank using a Talyrond 365. The results are shown in Figure 6 and Table 4. Where: CYLp-cylinder peak-the value of the largest positive local cylindrical deviation from the least squares reference cylinder, CYLv-cylinder valley-the absolute value of the largest negative local cylindrical deviation from the least squares reference cylinder, CYLt-cylinder peak to valley-the radial separation of two cylinders, coaxial with the fitted reference axis, which totally enclose the measured data.
From the measurement data obtained for the shank of the 3D printed tool, displayed in Figure 7 and Table 4, it is clear that the cylindricity error was 171.4 µm. The cylindricity error was mainly due to the form distortion (twelve lobes) observed in the cross-sections. The finishing by center grinding reduced the cylindricity error of the tool sh 7.6 µm. The cylindricity error of the shank after grinding resulted from the conicity The analysis of the shank cylindricity error confirmed the assumption that the min radius allowance should be 0.25 mm per side.
The next step was to assess the dimensional and geometric accuracy of holes with the two types of drill bits. Table 5 shows the mean values of the errors obtaine a ZEISS Prismo Navigator coordinate measuring machine. Each finished specime measured in five cross-sections and, then, the mean cylindricity error of the ho determined.
Another important parameter describing the drilling accuracy is the hole straig It was determined in four angular positions spaced every 90°. The measurement st is illustrated in Figure 6. Table 5. Average values of the geometric errors of the holes, obtained by the drill bits. The finishing by center grinding reduced the cylindricity error of the tool shank to 7.6 µm. The cylindricity error of the shank after grinding resulted from the conicity error. The analysis of the shank cylindricity error confirmed the assumption that the minimum radius allowance should be 0.25 mm per side.
The next step was to assess the dimensional and geometric accuracy of holes made with the two types of drill bits. Table 5 shows the mean values of the errors obtained with a ZEISS Prismo Navigator coordinate measuring machine. Each finished specimen was measured in five cross-sections and, then, the mean cylindricity error of the hole was determined. Another important parameter describing the drilling accuracy is the hole straightness. It was determined in four angular positions spaced every 90 • . The measurement strategy is illustrated in Figure 6.
The values provided in Table 5 indicate that for holes drilled at v c = 30 m/min and f n = 0.2 mm/rev, all errors, apart from roundness 1, were smaller for the additively manufactured tool when compared with the commercially made tool. It can, thus, be concluded that the holes drilled with the 3D printed drill bit were characterized by lower roundness, cylindricity, and straightness errors.
The lowest roundness error of 0.019 mm was obtained for holes drilled with the 3D printed tool at v c = 20 m/min and f n = 0.2 mm/rev, and at v c = 30 m/min and f n = 0.1 mm/rev. For the conventionally made drill bit, the lowest roundness error of 0.037 mm was observed at v c = 30 m/min and f n = 0.2 mm/rev; the error was 0.018 mm larger than that reported for the printed tool.
The hole cylindricity data suggest that the lowest error of 0.064 mm was reported for the 3D printed drill bit operating at v c = 20 m/min and f n = 0.2 mm/rev. For the HSS drill bit, the lowest cylindricity error was 0.031 mm larger; it reached 0.095 mm at v c = 30 m/min and f n = 0.2 mm/rev.
The lowest hole straightness error from drilling with the 3D printed tool was 0.021 mm and it was obtained at v c = 20 m/min and f n = 0.2 mm/rev. For the HK 11020480 HSS drill bit, the lowest hole straightness error was 0.021 mm larger, reaching 0.042 mm. Table 6 shows the mean square values of the forces at the x, y and z axes and the torque at the z axis measured during the hole drilling tests.
The results reveal that the mean values of the forces at the x and y axes and the torque at the z axis (F x -radial force, F y -tangential force, F z -axial force) were lower for the 3D printed tool when compared with those obtained for the HSS tool. However, the mean values of the force acting at the z axis were larger for the printed drill bit than for the HSS drill bit. The lowest mean value of the force at the x axis reported for the printed drill bit   8 illustrate the forces and torques, respectively, at the x, y, and z axes for drilling at v c = 20 m/min and f n = 0.1 mm/rev. Red represents the printed drill bit, while blue the HSS drill bit. In the diagrams in Figures 7 and 8, three characteristic stages can be distinguished. Stage 1 corresponds to the beginning of the drilling process (from second 6 until second 10), when the drill bit enters and gradually cuts into the workpiece until the full cutting diameter is reached. During stage 2 (from second 10 to second 39), the full diameter of the drill bit is engaged in the hole cutting. At stage 3 (from second 39 until the end), the drill bit exits the workpiece and returns to the starting position.
From Figure 8, it is clear that there are differences in performance between the printed tool and the HSS tool. For the conventionally made drill bit, forces acting on the system at the x and y axes are larger when the tool enters the workpiece; this stage lasts about 10 s longer than for the printed tool. Then, the forces stabilize and are similar for both tools. The diagrams in Figure 8 suggest smaller hole straightness and roundness errors for the printed tool. The forces acting at the z axis are more stable (with curves more linear in shape) for the printed drill bit rather than for the drill bit produced by Atron.
Analysis of Figure 9 reveals that diagrams of the torques at the x and y axes for drilling at v c = 20 m/min and f n = 0.1 mm/rev are similar to the diagrams of the forces (Figure 7). The signals registered in drilling at v c = 20 m/min and f n = 0.1 mm/rev show that the torque at the z axis was larger for the conventionally made drill bit. blue the HSS drill bit. In the diagrams in Figures 7 and 8, three characteristic stages can be distinguished. Stage 1 corresponds to the beginning of the drilling process (from second 6 until second 10), when the drill bit enters and gradually cuts into the workpiece until the full cutting diameter is reached. During stage 2 (from second 10 to second 39), the full diameter of the drill bit is engaged in the hole cutting. At stage 3 (from second 39 until the end), the drill bit exits the workpiece and returns to the starting position. From Figure 8, it is clear that there are differences in performance between the printed tool and the HSS tool. For the conventionally made drill bit, forces acting on the system at the x and y axes are larger when the tool enters the workpiece; this stage lasts about 10 s longer than for the printed tool. Then, the forces stabilize and are similar for both tools. The diagrams in Figure 8 suggest smaller hole straightness and roundness errors for the printed tool. The forces acting at the z axis are more stable (with curves more linear in shape) for the printed drill bit rather than for the drill bit produced by Atron. Analysis of Figure 9 reveals that diagrams of the torques at the x and y axes for drilling at vc = 20 m/min and fn = 0.1 mm/rev are similar to the diagrams of the forces (Figure 7). The signals registered in drilling at vc = 20 m/min and fn = 0.1 mm/rev show that the torque at the z axis was larger for the conventionally made drill bit.

Conclusions
The main aim of this article was to compare the performance of two twist drill bits: a conventionally made HK 11020480 HSS drill bit and a specially designed 3D printed drill bit fabricated by DMLM using maraging steel 1.2709. The hole roundness, cylindricity, and straightness errors were also analyzed.
The results of the comparative study can be summarized as follows: • Three-dimensional (3D) printed steel 1.2709 drill bits are suitable for drilling holes in polyamide 6 (PA6) and can be used as an alternative to HSS steel drill bits in the test range conducted; • Material allowances are required for 3D printed drill bits because of the insufficient accuracy of the AM process. The allowances need to be taken into account at the

Conclusions
The main aim of this article was to compare the performance of two twist drill bits: a conventionally made HK 11020480 HSS drill bit and a specially designed 3D printed drill bit fabricated by DMLM using maraging steel 1.2709. The hole roundness, cylindricity, and straightness errors were also analyzed.
The results of the comparative study can be summarized as follows: • Three-dimensional (3D) printed steel 1.2709 drill bits are suitable for drilling holes in polyamide 6 (PA6) and can be used as an alternative to HSS steel drill bits in the test range conducted; • Material allowances are required for 3D printed drill bits because of the insufficient accuracy of the AM process. The allowances need to be taken into account at the design stage while creating a CAD model. The minimum radius allowance for a drill bit 12 mm in diameter is 0.25 mm per side to achieve high geometric and dimensional accuracy of the cutting tool; • The length allowances, i.e., those along the tool axis, are required for center grinding (5 mm for a center hole at each end) and for facing (0.5−1 mm); • The dimensional and geometric accuracy of the holes made in the polyamide 6 (PA6) by the specially designed 3D printed drill bit were higher than that reported for the HSS drill bit; • The lowest hole roundness error of 0.019 mm was obtained for the 3D printed drill bit, when the conventionally made drill bit was used, the lowest hole roundness error was 0.018 mm higher; • The lowest hole straightness error reported for the 3D printed drill bit was 0.021 mm and it was achieved at vc = 20 m/min and fn = 0.2 mm/rev. By contrast, the lowest hole straightness error obtained with the same process parameters for the HK 11020480 HSS drill bit was 0.042 mm, which was twice as high as that obtained for the 3D printed tool; • The lowest hole cylindricity error measured for the 3D printed drill bit was 0.064 mm, for the HSS tool this parameter was 0.031 mm higher; • For the 3D printed drill bit, the lowest and the highest mean values of the force acting at the x axis were 7.16 N and 10.96 N, respectively; for the force acting at the y axis, the values were 7.55 N and 10.22 N, respectively. The lowest mean square values of the forces at the x and y axes reported for the HSS drill bit were 11.06 N and 11.07 N, respectively, while the highest were 11.61 and 11.51 N, respectively.